Unfortunately, many people require the assistance of a drainage system to remove fluids such as urine from their body. For example, a quadriplegic typically has no control over his/her own bladder and depends on a drainage system to remove urine and allow him/her to venture away from a restroom for extended periods of time. The drainage system stores fluids and allows a user to dispose of these fluids at a time convenient for the user.
FIG. 1 shows a conventional drainage system 20, described in U.S. Pat. No. 5,092,856 to Johnston, that includes a reservoir 22 for storing a fluid and a valve 24 to control the flow of fluid from the reservoir. FIG. 2 shows a cross section of the valve 24 in FIG. 1 in a closed position. The drainage system 20 also includes a catheter 26 for transferring fluid to the reservoir 22 a drain tube 28 for transferring fluid out of the reservoir 22 and a lever 30 for selectively opening and closing the valve 24. To drain the reservoir 22, one opens the valve 28 by moving the lever 30. To quit draining the reservoir 22, one closes the valve 28 by releasing the lever 30.
The valve 24 includes a spring 32 that biases the valve in a closed position. The spring 32 forces the plunger 34 toward the end 36 to pinch the drain tube 28 closed. To insure that the drain tube 28 is sufficiently pinched to prevent flow through the tube 28 when the valve 24 is closed, the spring exerts considerable force on the plunger 34. Consequently, to open the valve 24 and keep it open while the reservoir drains, a user must overcome the spring's force on the plunger 34.
Unfortunately, the strength and dexterity required to open and keep open the valve typically exceeds a quadriplegic's strength and dexterity. To assist the quadriplegic, electrically controlled and operated valves can be used. But, their use presents other problems. First, such valves require a power source, which can be expensive to maintain and can expire at a very inconvenient time. Second, if the valve fails for some reason, for example water or other types of fluid damage the valve or power source, the valve may stick in the open or closed position. Stuck in the open position, the valve will not allow the drainage system to store fluids for any length of time. And stuck in the closed position, the valve will not allow the drainage system to be drained without permanently opening the valve.
Thus, there is a need for a valve to control the flow of fluid from a reservoir, that requires minimal force and dexterity to open, keep open, and close, and remains closed when not operated by a user.